In many embedded control systems, and other computing systems, movement of data between peripheral devices and a host, or between peripheral devices, can be a significant amount of data traffic on the various buses that may exist in such systems. Moreover, some of this data traffic may carry information and commands for real-time critical systems. Thus, signal integrity becomes an important factor in accurate communication.
In some systems, to determine signal integrity it is important that the margin is known in a communication system when transferring data from one point to another either via electrical transmission lines or via an optical channel. As one example, in automotive high-speed digital communications, the car companies want to know whether there is still enough signal integrity margin in each of their communication links. Each element in the communication link can deteriorate under aging, mechanical stress, temperature stress, and combinations thereof. Elements in the link may include: a cable driver circuit, a common mode choke at the transmit side, a connector at the transmit side, a cable, inline connectors, a connector at the receiving side, a common mode choke at the receive end, an equalizer, a phase-locked loop (PLL) for data recovery, and printed circuit board (PCB) traces.
The inventors of this disclosure foresee a need for an easy, fast, and inexpensive method to diagnose the signal integrity margin before bit error rates rise to an intolerable level during run-time.